kill time

Meaning: You kill time when you do something to amuse yourself while waiting for something.

For example:

I had to kill time at the airport because of the delay so I bought a book of crossword puzzles.

We kill time on long trips by playing this game in which someone thinks of a country, and the next person has to think of another country that starts with the last letter of the first one, like Thailand, Denmark, Kenya, Afghanistan, Nepal, and so on.